Mobile devices such as cellular telephones, smart phones, and other handheld or portable electronic devices such as personal digital assistants (“PDAs”), headsets, MP3 players, etc. have become popular and ubiquitous. As more and more features have been added to mobile devices, there has been an increasing desire to equip these mobile devices with input/output mechanisms that accommodate numerous user commands and/or react to numerous user behaviors. It is of increasing interest that mobile devices be capable of detecting the presence of, and determining with some accuracy the position of, physical objects located outside of the mobile devices and, more particularly, the presence and location of human beings (or portions of their bodies, such as their heads or hands) who are using the mobile devices or otherwise are located nearby the mobile devices. By virtue of such capabilities, the mobile devices are able to adjust their behavior in a variety of manners that are appropriate given the presence (or absence) and location of the human beings and/or other physical objects.
While remote sensing devices such as infrared (or, more accurately, near-infrared) transceivers have been employed in the past in some mobile devices to allow for the detection of the presence and/or location of human beings and/or physical objects even when not in physical contact with the mobile devices, such sensing devices have been limited in various respects. In particular, some such near-infrared transceivers in some such mobile devices are only able to detect the presence or absence of a human being/physical object within a certain distance from the given transceiver (e.g., binarily detect that the human being/physical object is within a predetermined distance or proximity to the transceiver), but not able to detect the three-dimensional location of the human being/physical object in three-dimensional space relative to the transceiver. Also, some such transceivers in some such mobile devices are undesirably complicated or require large numbers of components in order to operate, which in turn renders such devices unduly expensive. Many such implementations are modular in type and thus require user to have prior knowledge of the module location in order to operate above the module, resulting in a less than optimum experience. Further, those systems are focused on a specific implementation of gesturing and not designed to be used as part of other systems such as side approach detection, eye tracking, facial illumination, and data transmissions.